<!DOCTYPE HTML>
<html>
<head>
<meta charset="utf-8">
<title>无标题文档</title>
<script>
var i=0;			//1.初始化

while(i<5)			//2.条件
{
	alert(i);		//3.语句
	
	//i=i+1;		//4.自增
	i++;
}
</script>
</head>

<body>
</body>
</html>
